I would like to redirect incoming HTTP requests to two different ports on different pools

Unfortunately, no. That's partly why this seems so difficult. There isn't anything to key off to make a pool decision, except for different ports. The client however will not know about the ports because they are only hitting port 80. I need to somehow redirect incoming requests from 80 to those two other ports, and do so in a round robin fashion, yet still allow for failure detection. I tried yesterday with GTM, using a translation at the GTM VS layer, but that didn't work....